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Updated: Sep 18, 2025
Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
Published on: December 16, 2013
Steric Control of Copper(II) Coordination by Carnosine: Role of the β-Alanyl Methylene Spacer
Xueyu Feng1, Chunyang Wang1, Yangfan He1
1Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian 116024, China.
Abstract:
Carnosine (β-alanyl-l-histidine), the shortest histidine-containing natural peptide in mammalian tissues, regulates crucial biological processes through Cu(II) chelation. Using a multitechnique approach combining potentiometric titration and UV-vis, EPR, FTIR, and 2D IR spectroscopy, we identified and characterized three distinct Cu(II)-carnosine complexes with pH-dependent speciation. Structural comparison with glycyl-l-histidine demonstrates that the extended methylene spacer of carnosine introduces unique steric constraints that (i) inhibits amide hydrogen substitution by Cu(II), (ii) facilitates formation of the binuclear species [Cu2LH-1]II, and (iii) promotes subsequent dimerization to [Cu2L2H-2] under acidic to neutral conditions. At alkaline pH, the protonation state of carnosine N-terminus serves as a critical regulator of Cu(II) coordination geometry, dictating metal binding affinity and determining site preference between N- and C-terminal coordination motifs.
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